UI Grid CSS not working

I tried to create a grid using UI grid (Recent version of ngGrid) which is unstable version and integrated in my current project.

It is Not correctly displaying the (icon angle down and row selected icon) as needed While including the CSS file in project (by downloading the file and uploading) its giving me display errors as shown below.

But, if i directly give the web url for CSS file in my project...it is displaying correctly.